Anyone played this game? I'm planning to make a game like it using C2 but I was just wondering if it would be alright to use their sprites/sounds etc. on my game. Plus, if it goes well, I'm also planning to put it in Chrome Web Store.

Counterstrike 2D itself is free and you can even make your own maps and custom sprites and tilesets but I was thinking since its going to be in Chrome Web Store (which might give me income), its going to be a commercial game in a way.

According to the author's disclaimer you should contact him to ask for the permission.It's not very clear what part of the assets he created. I guess you should directly get in touch with him to see by yourself what assets he'd allow you to reuse.